The object of this study is to identify and to evaluate the safety of intravenously administered pantoprazole that would decrease and maintain acid secretion at less than 10 mEq/hr in patients with Zollinger-Ellison syndrome with or without multiple endocrine neoplasia type I (MEN-I) syndrome who have not undergone partial gastrectomy (<5 mEq/hr in patients with previous gastric surgery) Study terminated October 1998. Data is being analyzed.